The aim of this project is to determine if abnormalities of fixation, eccentric fixation and unstable fixation, are the cause of decreased visual function in amblyopia. To test this hypothesis a combination of several techniques will be used: monitoring eye position using differential reflectance from the limbus, a new method using the visually evoked potential to determine the position of the center of the fovea relative to an eye position reference with an accuracy of 7 minutes of arc in emblyopic eyes, and a 2 alternative forced choice psychophysical method to measure increment threshold, spatial summation coefficients, and visual acuity. The combined use of these techniques will allow test stimuli to be presented to the center of the fovea and evaluation of performance in relation to measured eye position instability. If some or all amblyopes have normal or near normal visual function when targets are presented to the center of the fovea, it might be possible to teach these amblyopes to normalize their fixation and regain good visual function using modern biofeedback techniques.